Digital timepiece

ABSTRACT

A digital timepiece is disclosed in which characters to indicate the minutes of the first digit and of the second digit and of the hour are formed by light transmitting film in drums; a plurality of drums are disposed in parallel and driven intermittently by a synchronous motor and a source of light in each drum directly irradiates the characters.

United States Patent lzawa et al.

{Ill} DIGITAL TIMEPIECE Inventors: Masao lzawa; Kiyoto Ohlawa. both of SakakLmachi; Yookichi Yuasa, Tokura, all of Japan Assignee: Agatsuma Seiki K. K.. Japan Filed: Nov. 20, 1973 Appl. No.1 417,493

Foreign Application Priority Data Nov. 24 l972 Japan 47-l34554 June 1. l973 Japan .r 48-63945 July 6 1973 Japan 48-79800 US. Cl. 58/50 R; 58/l25 C Int. Cl G04b 19/30; G04b l9/02 Field of Search... 58/4 R, 4 A, 6, 50 R, l25 C 58/127 R, 125 R June 3, 1975 [56] References Cited UNITED STATES PATENTS 3rl79 003 4/1965 Tompson 58/50 R 3.671787 7/1972 Kauaccvic 58/50 R Primary Examiner-Edith Simmons Jackmon Attorney, Agenl, or FirmWilliam Anthony Drucker i 1 ABSTRACT A digital timepiece is disclosed in which characters to indicate the minutes of the first digit and of the second digit and of the hour are formed by light transmitting film in drums; a plurality of drums are disposed in parallel and driven intermittently by a synchronous motor and a source of light in each drum directly irradiates the characters l0 Claims, 8 Drawing Figures PATENTEDJUH 3 1975 SHEET FATE??? H 3.886725 SHEET 3 Fig.6

|| Illlllllll PATENTEUJUHS 1925 3888725 SHEET 4 DIGITAL TIMEPIECE SUMMARY OF THE lNVENTlON A digital timepiece is composed by rotatably providing in parallel a plurality of drums had the indication characters which are formed by the light transmitting portions, attaching an interlocked rotary body that will be driven successively and intermittently by an synchronous motor to each of these drums, installing a light on each of these drums, and allowing each ofindication characters provided on said drums to the opening formed on the cover for each unit for the purpose that clear time indication can be watched even in day time or in a sufficiently bright chamber.

BACKGROUND OF THE lNVENTiON This invention relates to a digital timepiece and provides a digital timepiece in which time indication is represented by characters in a succesive and intermittent manner being driven by an synchronous motor, said digital timepiece having a novel mechanism that displays clear time indication.

A variety of digital timepieces have so far been proposed and placed in practical use. But their digital indication mechanisms are not all satisfactory for enabling one to recognize the time indication. For example, a common indication mechanism consists of lighting the indication surfaces from the side. in such a case, however, the quantity of light from the source of light incident from a narrow clearance between the indication opening on the covering and the adjacent indication plate on the back side, is naturally limited, and in addition, the incident light undergoes reflection over the entire area of the indication surface and the indication characters intended to be seen may only be matched as characters written on said surface; it is hard to see clear time indication. Besides, in a mechanism in which indication members are interlocked with each other and driven intermittently, the interlocking mechanism to halt the indication at a determined position other than the driving moment, results in very complex setup, and the engaging and disengaging action of the self-locking plate produces noise and disturbs sleeping, furthermore in case the time indication has differed from the normal time, the time-adjusting operation is very clumsy and cumbersome since the total mechanism to indicate the hour and minute is based on a series of interlocked mechanisms.

BRIEF DESCRIPTION OF THE INVENTION This invention is to provide an advantageous digital timepiece eliminating the above-mentioned disadvantages and drawbacks inherent to earlier devices. That is, the principal object of this invention is to provide a digital timepiece which allows very clear recognition of time indication. For this purpose, according to this invention, the indication characters to indicate the minutes of the first digit and of the second digit and the hour are formed by light transmitting film in drums, and a plurality of these cylinders are rotatably disposed in parallel and are driven successively and intermittently by a synchronous motor, and a source of light is installed in each of these drums so that light said source of light may directly irradiate the characters, and, in this way, make it possible to obtain clear indication, being essentially different from earlier counterparts in which characters are indirectly irradiated with limited amount of reflected light. According to such a contrivance of this invention, the indication can clearly be seen even in day times or in a bright room, being quite different from the time indication systems, of conventional digital timepieces and thus providing a novel digital timepiece.

Another object ofthis invention is to provide a digital timepiece in which the above-mentioned drums assume invariably correct indication positions and are appropriately rotated at a time of determined and intermit tent motion with a relatively simple mechanism, thereby eliminating production of noise. In a digital mechanism of the type in which a continuous rotary motion of the synchronous motor is transmitted to a rotary member in such a manner that a digit of minute indication is advanced for every minute, and the motion of the rotary member which advances a digit of minute indication is intermittenly transmitted to the second and third rotary members to effect time indication, it is essential to halt the rotation except at the moment of said rotating period and to allow rotation only at said rotating period, as incidental rotation to a series of rotary members other than the period of intermittent ro tation will greatly disturb the relation of time indication. For this reason, earlier digital mechanisms of this type are necessarily provided with a self-locking mechanism using a ratchet or a self-locking mechanism combined with a resilient member. But such conventional methods are complex in construction not only requiring a clumsy arrangement and an assembly of individ ual parts concerning a plurality of rotary members but also accompanied by the production of tick tack noise when the selflocking members are engaging and disengaging, and at least tending to disturb sleeping.

In this invention, a mechanism to halt the rotation other than at the determined period of rotation mentioned above is set up utilizing the interlocked rotary mechanism itself which rotates being interlocked together, and by doing so, it is allowed to ensure the halted or locked state other than during the determined period of intermittent rotation, the setup not needing any particular self-locking pin, ratchet, or resilient member, thus being simple in construction and naturally avoiding the possibility of producing noise.

A still further object of this invention is to make it possible to adjust the time indication easily and within a short time, despite the above-mentioned series of interlocked mechanism. Digital timepieces of this kind feature very precise mechanism, producing a time deviation or error if several seconds in a week at best, accordingly adjustment of time indication may not partic ularly be needed, unless hit by a power failure. But in a series of locked relation, although a digit of minute indication or two digits of minute indication (which is of minimum unit indication) may be easy, it becomes increasingly hard to adjust the hour indication interlocked thereto, particularly when adjusting as much time deviation as l0 hours. For example, a digit of minute indication can be adjusted instantaneously with a single rotation of the adjusting member, but 6 such rotation will be required to adjust hour indication. The adjustment of time deviation by as much as 10 hours will then require a tremendous amount of times of such rotations. Therefore, in order to eliminate such inconvenience, this invention makes it possible to adjust the minute indication and the hour indication independently thereby maintaining the above-mentioned series of interlocked relation. so that the aimed accurate time indication can be obtained with a very simple adjustment operation.

Many other concrete features and effects of this invention will become apparent from the following description of embodiments and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of this invention. and in the drawings;

FIG. 1 is a perspective view showing an example of the digital timepiece according to this invention.

FIG. 2 is a side view thereof.

FIG. 3 is a partial cross-sectional view showing part of the covering FIG. 4 is a perspective view showing the CIISHSSCITP bled state of the constituent members in the covering.

FIG. 5 is a plan view of the interlocking mechanism.

FIG. 6 is a side view of showing disassembled state of the interlocking member shown in FIG. 5,

FIG, 7 is a perspective view showing the disassembled state of the time-indication adjustment mechanism. and

FIG. 8 is a perspective view showing a modification of the rotary drum.

DETAILED DESCRIPTION OF THE INVENTION Illustrating the invention with reference to the accompanying drawings. eg. with reference to FIGS. 1 and 2. the digital mechanism of this invention is enclosed in the front and rear covering 90 and 91. These coverings 90 and 91 are engaged together at the engaging step 92 formed at the edge thereof. and the two coverings are securely held to an assembly by means of a connection rod 93 fitted to the lower part of the covering 90 thereby screwing in a stopper 94 from the side of the other covering 91. At the lower central part of these coverings 90, 91 are provided protrusions 95 which hold the lateral axis 97 provided on the bed 96; hence as shown by chain dotted lines in FIG. 2, the coverings 90, 91 are appropriately tilted with respect to the supporting face of the bed 96, so that the indication surface 100 which is a front surface of the covering 90 may be set appropriately inclined upward or downward. On the indication surface 100 are provided an opening 101 for indicating hour. and openings 102 and 103, respectively. for indicating two digits of minute indication and one digit of minute indiation. and an opening 104 for confirming the operating state. in the order from left toward right as shown in FIG. 1. The openings 102 and 103 for indicating the minutes are provided in a relatively large recess 105 to encompass them. and other openings 101 and 104 are provided in their respective recesses. Inside the series of these openings 101-104 is provided a transparent plate 98. On said transparent plate 98 are formed lens portions 99in a protruding manner at the positions corresponding to the above-mentioned openings 101-103; i.e.. in the case shown. the lense portions protruding in an arc form viewed in the vertical direction are formed to fit to the opening MIL-I03. At the opening 104 or in the inside representing said opening I04 is fitted a transparent part 106 formed with a small diamondshaped pyramidal aslant surface. The above-mentioned lens 98 portions 99 are to enlarge the angular range within which the characters indicated in the openings 101-103 can be seen. and the transparent part 106 on which is formed a small diamond-shaped pyramidal aslant surface gives instantaneous change to the light emitted from the rotary body rotating continuously. thereby not only aiding one to recognize the operative condition of the mechanism but also to optically provide the motion of second. as will be mentioned later.

FIG. 4 shows the disassembled state of the inner mechanism contained in the coverings 90, 91. A frame is set up by fastening a top plate 8 to the support poles studded on the four corners of a bottom plate 7 by means of connectors 80. And on such a bottom plate 7 are arranged a first rotary drum 1 which indicates the operative condition. a second rotary drum 2 which indicates a digit of minute indication. a third rotary drum for two-digit minute indication. and a fourth rotary drum 4 for hour indication. These rotary cylinders 1-4 acquire an interlocked relation as will be mentioned later. At the back part of the bottom plate 7 is formed a vertical wall 71, and behind the vertical wall 71 is installed a synchronous motor 5. And. by connecting said motor 5 to a required power source through commonly used electric wires, the motor pinion 50in rotated continuously. By such a continued rotation of the motor pinion 50 is rotated the first rotary drum 1, and the second to fourth rotary drums 24 are rotated intermittently.

These rotary drums 14 are all arranged vertically on the bottom plate 7 as shown in FIG. 4. and are supported rotatably between the bottom plate 7 and the top plate 8 by means of vertical shafts 10, 20. 30 and 40. The first rotaty drums 1 is of a drum shape and is formed with a light transmitting material and is wound over its periphery with an opaque film 12 having lighttransmitting parts 13 provided stepwise in the up-anddown direction maintaining a definite distance. The first rotary drum 1 is given a rotary motion via an inter locking gear 51 meshed with said motor pinion 50, a crown gear 52 concentric therewith, an intermediate gear 53 meshed with said crown gear 52, and an inter locking gear 15', a small gear 14 at the bottom of the rotary drum 1 is engaged with the interlocking gear 15 so that continued rotation is provided. The interlocking gear 51 and the crown gear 52 are rotatably attached to the vertical wall 7 by means of a support member 55. The second to fourth rotary drums 2-4 are of prism forms; the rotary drum 2 is a regular decagon. the rotary drum 3 is a regular hexagon. and the rotary drum 4 is a regular duodccagon. each surface thereof being provided with characters to indicate the minutes or the hours in a manner of a slit-like punched hole 9, and the inner side thereofis coated with light-transmitting film, especially semi-transparent film 21, 31. or 41. It is desired that these films 21, 31, and 41 are colored red, yellow. green or in other colors for easy watching. The interlocking construction to transmit intermittent rotation from said intermediate gear 53 to each of these rotary drums 2-4 will be mentioned later with reference to FIGS. 5 and 6. At the foreground of said top plate 8 are provided four openings 81 for inserting lighting bulbs 86, and behind these openings 81 are attached reflectors 82 curved in an arc form and hung down ward. To the top plate 8 is attached a printed plate through an electric insulation plate 84 by means of connectors 89, and said lighting bulbs 86 electrically connected to said printed plate 85 are inserted in the rotary drums I4 through holes 84a and openings 81. On the printed plate 85 are provided resistor 88 for each lighting bulb 86 to secure required light quantity.

The aforesaid intermittent rotary motion that will be given to said rotary drums 2-4 is obtained by the mechanism shown in FIGS. 5 and 6. That is. on the intermediate gear 53 is mounted concentrically another rotary member 56 having an engaging pin 58 at the tip of the protrusion 57. The engaging pin 58 is allowed to protrude toward the cogs 23 of the engaging plate 22 concentric with the rotary drum 2. and steps up the cogs 23 of the engaging plate 22 one by one for every rotation of the rotary member 56; i.e.. the face of the rotary drum 2 is rotated one by one for every minute. The rotation of said motor 5 rotates the intermediate gear 53 continuously, and turn once every minute by means of teeth which are arranged on said engaging plate 22. and the small lighbtransmitting part I3 of said rotary drum which rotates continuously at such a rate that the one light-transmitting part 13 passes the transparent part 106 every second. On the engaging plate 22 is provided another engaging protrusion 24 which engages and disengages with the engaging groove 26 of the first intermediate rotary member 25. Said intermediate rotary member 25 has an arc-shaped recess 27 between each engaging groove 26 at the periphery. The recess 27 engages with the periphery of the circular protrusion 28 formed on the engaging plate 22 except when the engaging protrusion 24 has engaged with the engaging groove 26. Hence when the intermediate rotary member 25 is not actuated by the engaging protrusion 24, the circular protrusion 28 helps interrupt the rotation of the intermediate rotary member 25. On the disc 25a placed concentrically on the intermediate rotary member 25 are erected engaging pins 29 corresponding to the positions of said engaging grooves 26; the engaging pins 29 are to engage or disengage with the engaging grooves 33 of the engaging plate 32 formed at a single unit with the rotary drum 3. The distance between the engaging pins 29 is equal to the distance of the engaging grooves 33. Hence each engaging pin 29 steps up the engaging groove 33 one by one; any oneof the engaging pins 29 has necessarily been engaged Wlth any one of the engaging grooves 33 so that engaging plate 32 and rotary drum 3 will not move disorderly. On another rotary disc 34 provided concentric with the en gaging plate 32 is provided an engaging part 35 that will engage and disengage with the engaging groove 37 of another intermediate rotary member 36. Between each engaging groove 37 of said intermediate rotary member 36 is formed an arc-shaped recess 38. When the engag ing part 35 is not engaging with the engaging groove 37, these recesses 38 engaging with said rotary disc 34 help to interrupt the rotation of the intermediate rotary member 36, like the abovemientioned engagement of the circular protrusion 28 with the recess 27. On the disc 36a formed together with the intermcdiaterotary member 36 are erected six engaging pins 39 which engage and disengage with 12 engaging grooves 43 pro vided on the engaging disc 42 which is mounted together with the rotary drum 4. The d stance between the engaging pins 39 is equal to the distance between the engaging grooves 43. Hence the engaging pm 39 which i stepped up one by one for every rotation ofthe engaging disc 32 via the engaging disc 42 rotates the wheel 63 and vertical shaft 40 to cause the rotary disc 4 to be rotated by one face. as will be mentioned later with reference to FIG. 7.

As will be clear from the aforedescribed setup. the rotary member 56 by means of the engaging protrusion 58 steps up the cogs 23 of the engaging plate 22 one cog by one cog. And as will be clear in FIG. 5, the cogs 23 have an engaging face 230 in the radial direction and an aslant face 23b aslant at the back side. which serve to effect desirable correcting action when each face of the rotary cylinder 2 is not facing normally to the opening 103. That is, since the engaging protrusion 58 has not usually been engaged with the cog 23, there is much likelihood that the rotary drum 2 by some reason may not often normally face the opening I03. But in such a case, the moment of engagement between the engaging protrusion 58 and the engaging face 231: may lag behind. or proceed a little before. the normal period, and in any case. the engaging and disengaging position between the engaging protrusion 58 and the engaging face 23a is the same. so that another rotation of the rotary member 56 causes the rotary drum 2 to face nomally to the opening 103. The engaging plate 22 which is advanced by one tooth for every minute. via the intermediate rotary member 25 steps up the engaging disc 32 and the rotary drum 3 by one face for every rotation of the engaging plate 22 tor for every 10 min utes). And via the intermediate rotary member 36. the rotary drum 4 is stepped up by one face for every rotation (every 60 minutes) ofthc rotary drum 3 to display the hour indication. In this way, each of prism-shaped rotary drum 24 helps display the character indication maintaining correct relation and through the lens portion 99, so that characters may be watched over a wide visual-angle range.

According to this invention, since the engaging protrusion 58 engages with the cogs 23 only for a brief period oftime, the time correction can be effected appropriately by turning the engaging teeth 62 of the adjustment wheel 6 to turn the gear 60 formed in concentric with the engaging plate 23 via the intermediate gear 61. And the adjustment wheel 6 has been partly protruded from the back of the covering 91 (or 90) for smooth adjustment, like the adjustment means of common digital timepieces of this type. And in this invention, the adjustment can be effected to the rotary drum 4 which displays hour indication, in addition to adjustment for minute indication. And for this purpose, as will be seen from FIG. 7, the rotary drum 4 is attached to the end of said vertical shaft 40, and to the vertical shaft 40 have been fitted a wheel 63 which has an engaging pawl 67 pivotally supported by the attaching shaft 69, and an adjustment operation wheel 64 that will be actuated in mesh with the adjustment wheel 65 part of which is protruded beyond the covering 91 (or like the said adjustment wheel 6. Also, between the rotary drum 4 and the wheel 63 is loosely inserted an engaging disc 42 that engages with the engaging pin 39 of said intermediate rotary member 36, and on one side of said engaging plate 42 is formed a self-locking ratchet 68 which will engage with said engaging pawl 67.

If the engaging disc 42 is rotated by turning the said disc 36a, the wheel 63 will then be rotated via the engaging pawl 67 engaged with the ratchet 68. so that the rotary drum 4 is turned \ia the vertical shaft 40 to which has been fitted the wheel 63, as mentioned above. thereby displaying hour indication. Here. by rotaing the vertical shaft 40 by means of the adjustment wheel 65 via the adjustment operation wheel 64 in the direction opposite to the rotating direction by means of said disc 36a. the rotary drum 4 will be rotated in the direction opposite to the aforedescrihed instance. thus allowing free adjustment or setting of the hour indica tion. In this case. a tick tock sound may be produced during adjustment operation between the engaging pawi 67 and the ratchet 68, which noise during the ad justment. however. will not at all be of offensive nature. Also. the engaging disc 42 will have been secured firmly during such adjustment of the rotary drum 4. without affecting the indication of the second and third rotary drums 2 and 3.

The invention illustrated in the foregoing may be put into practice by effecting appropriate modification without departing from the spirit of this invention What I claim is:

l. A digital timepiece comprising an intermediate gear rotated continuously by a synchronous motor, an engaging protrusion integral with said intermediate gear, a series of intermittently rotative members arranged on a first plate and actuated in successive order and intermittently by said engaging protrusion. at least three rotary drums mounted on said intermittently ro tative members. a plurality of light sources arranged on a second plate and positioned in each said rotary drum, and a cover enclosing and holding said motor. intermittently rotative members. rotary drums and light sources. said rotary drums being adapted to display characters for single digit of minute indications, two digits of minute indications and hour indications, said characters being formed of lighbtransmitting material. said covering being provided with a plurality of opening for displaying an indication unit of each of said rotary drums, and the light rays emitted from said light sources being emitted directly toward the outside through the characters of said lighttransmitting con struction and the openings of the covering.

2. A digital timepiece according to claim 1 wherein a reflector is provided at the back of each light source, and the light ray from said light source is concentrated onto the characters and the openings of the covering.

3. A digital timepiece according to claim 1 wherein said rotary drums are polygonally shaped, each face of said rotary drums being formed with said characters of lighHransmitting material, and the openings of the covering being provided with a lens.

4. A digital timepiece, according to claim 1, wherein each of said rotary drums has characters with holes covered at the inside by semi-transparent film.

5. A digital timepiece according to claim 1, wherein each of said rotary drums has characters on which are arrayed small holes.

6. A digital timepiece according to claim 1, wherein each rotary drum is interlocked with an intermediate gear rotating continuously, at light-transmitting member formed in pyramidal recess shape being attached to the opening of the covering positioned in front of said rotary drum. and a source of light being inserted in said rotary drum to indicate the movement of the mechanism in continuous rotation, and the optical change produced through said pyramidal recess indicating passage of one second.

7. A digital timepiece according to claim I. wherein a ratchet wheel formed with engaging portions in the radial direction and aslant portions having a large slope at the back is disposed to correspond to the face of the rotary drum indicating the single digit of minute. and said rotary drum is attached to the engaging plate that will be actuated by intermittent engagement with the engaging protrusion formed on the intermediate gear. in order that even where said rotary drum is stopped without normally facing the opening of the covering. the stopped position may be corrected by the rotation of said intermediate gear.

8. A digital timepiece according to claim 1, wherein the engaging parts, to prevent random engagement with each other during periods outside the determined period of intermittent movement, are formed between the driving rotary member and the driven rotary member with a series of intermittently rotative members consisting of at least three rotary drums.

9. A digital timepiece according to claim 1, wherein an engaging protrusion formed at the protruding part of the intermediate gear is allowed to intermittently engage with the teeth of the engaging plate attached to the rotary drum which displays a single digit of minute indication, and an adjustment wheel part of which protrudes out of the covering is engaged via an intermediate gear with the gear formed on said engaging plate, and another adjustment wheel is engaged with the gear mounted on the rotary drum which displays hour indication, so that minute indication and hour indication can be adjusted separately.

10. A digital timepiece according to claim 7, wherein i. an engaging plate that is driven upon intermittent engagement with the engaging pin of the disc which rotates as a result of being interlocked with the rotary drum to display two digits of minute indication, and

ii. a wheel are loosely mounted on the vertical shaft integrally attached to the rotary drum for hour indication, a self-locking ratchet being formed on said engaging plate as a single unit, an engaging pawl which engages with said self-locking ratchet being pivotally attached to said wheel, another adjustment operation wheel being firmly attached t said vertical shaft, and part of the adjustment wheel which engages with said another adjustment opera tion wheel being exposed externally of the cover. 

1. A digital timepiece comprising an intermediate gear rotated continuously by a synchronous motor, an engaging protrusion integral with said intermediate gear, a series of intermittently rotative members arranged on a first plate and actuated in successive order and intermittently by said engaging protrusion, at least three rotary drums mounted on said intermittently rotative members, a plurality of light sources arranged on a second plate and positioned in each said rotary drum, and a cover enclosing and holding said motor, intermittently rotative members, rotary drums and light sources, said rotary drums being adapted to display characters for single digit of minute indications, two digits of minute indications and hour indications, said characters being formed of light-transmitting material, said covering being provided with a plurality of opening for displaying an indication unit of each of said rotary drums, and the light rays emitted from said light sources being emitted directly toward the outside through the characters of said light-transmitting construction and the openings of the covering.
 1. A digital timepiece comprising an intermediate gear rotated continuously by a synchronous motor, an engaging protrusion integral with said intermediate gear, a series of intermittently rotative members arranged on a first plate and actuated in successive order and intermittently by said engaging protrusion, at least three rotary drums mounted on said intermittently rotative members, a plurality of light sources arranged on a second plate and positioned in each said rotary drum, and a cover enclosing and holding said motor, intermittently rotative members, rotary drums and light sources, said rotary drums being adapted to display characters for single digit of minute indications, two digits of minute indications and hour indications, said characters being formed of light-transmitting material, said covering being provided with a plurality of opening for displaying an indication unit of each of said rotary drums, and the light rays emitted from said light sources being emitted directly toward the outside through the characters of said light-transmitting construction and the openings of the covering.
 2. A digital timepiece according to claim 1 wherein a reflector is provided at the back of each light source, and the light ray from said light source is concentrated onto the characters and the openings of the covering.
 3. A digital timepiece according to claim 1 wherein said rotary drums are polygonally shaped, each face of said rotary drums being formed with said characters of light-transmitting material, and the openings of the covering being provided with a lens.
 4. A digital timepiece, according to claim 1, wherein each of said rotary drums has characters with holes covered at the inside by semi-transparent film.
 5. A digital timepiece according to claim 1, wherein each of said rotary drums has characters on which are arrayed small holes.
 6. A digital timepiece according to claim 1, wherein each rotary drum is interlocked with an intermediate gear rotating continuously, a light-transmitting member formed in pyramidal recess shape being attached to the opening of the covering positioned in front of said rotary drum, and a source of light being inserted in said rotary drum to indicate the movement of the mechanism in continuous rotation, and the optical change produced through said pyramidal recess indicating passage of one second.
 7. A digital timepiece according to claim 1, wherein a ratchet wheel formed with engaging portions in the radial direction and aslant portions having a large slope at the back is disposed to correspond to the face of the rotary drum indicating the single digit of minute, and said rotary drum is attached to the engaging plate that will be actuated by intermittent engagement with the engaging protrusion formed on the intermediate gear, in order that even where said rotary drum is stopped without normally facing the opening of the covering, the stopped position may be corrected by the rotation of said intermediate gear.
 8. A digital timepiece according to claim 1, wherein the engaging parts, to prevent random engagement with each other during periods outside the determined period of intermittent movement, are formed between the driving rotary member and the driven rotary member with a series of intermittently rotative members consisting of at least three rotary drums.
 9. A digital timepiece according to claim 1, wherein an engaging protrusion formed at the protruding part of the intermediate gear is allowed to intermittently engage with the teeth of the engaging plate attached to the rotary drum which displays a single digit of minute indication, and an adjustment wheel part of which protrudes out of the covering is engaged via an intermediate gear with the gear formed on said engaging plate, and another adjustment wheel is engaged with the gear mounted on the rotary drum which displays hour indication, so that minute indication and hour indication can be adjusted separately. 